Roll tap drill size chart

Roll taps, also called ‘form taps,’ have one continuous spiral thread on the tap and do not have flutes. They reform the material inside the hole rather than cutting it away. This typically makes them more durable than cut taps and provides a stronger thread in the material.

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Cut tap drill size

Cut taps are generally a cheaper option than roll taps and can be used in a wide variety of materials. However, the material being threaded will also chip and create debris. Those chips can be pulled out of blind holes by using a spiral flute cut tap.

“You can use it more often, we’ll say, before you’ll want to replace it,” Butler says. “That’s why so many machine shops want to use a roll tap.”

John Butler, a Martin Supply Regional Account Manager and Certified Fastener Specialist, explained some of those differences on the Fully Threaded Radio Podcast.

Cut tap vs roll tap

“A cut tap is actually going to cut away material after you’ve drilled the hole,” Butler says. “As it puts threads inside the material, it will cut away a portion and give you a very defined, more of a diamond-shaped thread.”

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Form tap vs cut tap

Despite being versatile and cost-efficient, cut taps also typically have a shorter tool life and will have to be replaced more often. Because the cut tap is literally cutting the material, it can become dull and worn rather quickly.

Forming Tap

When forming an internal thread, cut taps and roll taps are two of the most popular options. Both taps have advantages and disadvantages, and the right option for you may depend on the material being threaded.

Just like with most other tools, the right tap for your job depends on a number of outside factors including material, application, and desired thread characteristics.

Workshops for Warriors is a 501(c)(3) nonprofit school founded in 2008. Its mission is to place veterans and wounded warriors into advanced manufacturing careers by providing them with industry-leading training, nationally recognized credentials, work experience and job placement. Training is provided at no cost to veterans. We are rebuilding America’s advanced manufacturing workforce, one veteran at a time with a team of passionate, enthusiastic professionals who want to make a difference in the lives of those we serve, their families, and our country.

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Roll taps should not be used when dealing with a material that is especially hard, such as cast iron, or soft, such as nylon or plastics. If the material is too hard, it may fracture and break. If it is too soft, it may eventually become displaced.